Congratulations - what an exciting time! There's no way to tell just from hcg levels, so you'll have to wait until the ultrasound. There is about a 10% chance of having multiples. Did you get any ultrasounds while on the Clomid? I took Clomid, got an ultrasound that showed I had 2 viable eggs on each side, and still only have 1 baby in my belly :) Best of luck!